Heat exchanger assembly having split mini-louvered fins

ABSTRACT

A heat exchanger assembly is provided having at least one header, a plurality of spaced apart fluid tubes in hydraulic communication with the header, and a plurality of corrugated fins disposed between the tubes. The corrugated fins include a planar portion having a louver segment defined between a pair of primary slits, in which the louver segment includes an intermediate slit splitting the louver segment into a pair of mini-louvers. The mini-louvers are counter-offset such that one of the mini-louvers is on one side of the planar portion and the other one of the mini-lover is on the other side of the planar portion. The mini-louvers may be pivoted about their respective junctures such that each of the mini-louver segments is oblique relative to the planar portion.

CROSS REFERENCE TO RELATED APPLICATION

This Application is a continuation-in-part of U.S. patent applicationSer. No. 12/221,705, filed on Aug. 6, 2008, titled LOUVERED AIR CENTERFOR COMPACT HEAT EXCHANGER, the disclosure of which is incorporatedherein by reference in its entirety.

FIELD OF THE INVENTION

The invention relates to heat exchanger assemblies, particularly to heatexchangers having fins, and more particularly to air cooled heatexchangers having louvered fins.

BACKGROUND OF INVENTION

Air cooled heat exchanger assemblies for automobiles are used fortransferring heat from various working fluids, such as an enginecoolant, an engine lubricating oil, an air conditioning refrigerant, anda transmission oil. A typical air cooled heat exchanger assemblyincludes an inlet header, an outlet header spaced from the inlet header,a plurality of fluid tubes hydraulically connecting the inlet and outletheaders, and a plurality of corrugated fins disposed between adjacentfluid tubes. The core of the heat exchanger assembly is defined by theplurality of fluid tubes and the corrugated fins disposed betweenadjacent tubes. A stream of air is directed through the core of the heatexchanger assembly typically by a cooling fan or motion of theautomobile. As the stream of air flows across the fins, heat in a fluidflowing through the fluid tubes is conducted through the walls of thetubes, into the fins, transferred to the stream of air flow.

Various types of fins and louver designs are known in the art with theobject of increasing the heat transfer efficiency of the heat exchangerassembly. Examples of these designs include increasing the numbers oflouvers on a planar portion of the fin, forming louvers at apredetermined angle relative to the planar portion of the fin, forminglouvers above and below the planar portion of the fin, and disposinglouvers at predetermined locations on the planar portion of the fin toalter the air flow pattern through the core to increase the heattransfer coefficient of air encountered by the fluid tubes and fins.

It is desirable to continuously improve fin and louver designs for aheat exchanger assembly to increase the heat transfer efficiency bymaximizing the heat transfer coefficient of air encountered by the fluidtubes and fins while minimizing the pressure drop through the core.

SUMMARY OF THE INVENTION

In concordance with the instant disclosure, a heat exchanger assembly isprovided having at least one header, a plurality of spaced apart fluidtubes in hydraulic communication with the header, and a plurality ofcorrugated fins disposed between the tubes. The corrugated fins includea planar portion having a louver segment defined between a pair ofprimary slits, in which the louver segment includes an intermediate slitsplitting the louver segment into a pair of mini-louvers. Themini-louvers are counter-offset such that one of the mini-louvers is onone side of the planar portion and other one of the mini-lover is on theother side of the planar portion. The mini-louvers may be pivoted abouttheir respective junctures such that each of the mini-louvers is at anangle oblique relative to the planar portion.

The counter off-setting of the mini-louvers onto both sides of theplanar portion allows the mini-louvers to extend a greater distance fromthe planar portion into the air-flow channel than what a single largerlouver would allow. The greater louver penetration into the air flowchannels increases the distance that the air flow has to travel andincreases the number of boundary layer interruptions that the air flowhas to encounter, thereby increasing heat transfer efficiency. Theintermediate slit separating the first from the second mini-louver ineach pair of mini-louvers defines an air flow passageway, which allowsgreater air flow efficiency and less air pressure drop for air flowthrough the core of the heat exchanger assembly.

Further features and advantages of the invention will appear moreclearly on a reading of the following detailed description of anembodiment of the invention, which is given by way of non-limitingexample only and with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention will be further described with reference to theaccompanying drawings in which:

FIG. 1 shows a perspective front view of an exemplary embodiment of aheat exchanger assembly having corrugated fins with louvers.

FIG. 2 shows a perspective view of single louvered fins known in theart.

FIG. 3 is a detailed perspective view of the prior art single louveredfins of FIG. 2.

FIG. 4 shows a perspective view of an exemplary embodiment of splitmini-louvered fins of the current invention.

FIG. 5 is a detailed perspective view of the split mini-louvered fins ofFIG. 4.

FIG. 6 is a schematic cross-sectional view of single louvered fins ofFIG. 3 along line 6-6.

FIG. 7 is a schematic cross-sectional view of the split mini-louveredfins of FIG. 5 along line 7-7.

FIG. 8 is a schematic cross-sectional view of an alternative embodimentof the split mini-louvered fins.

FIG. 9 is a schematic cross-sectional view of an alternative embodimentof the split mini-louvered fins of FIG. 5 along line 9-9.

DETAILED DESCRIPTION OF INVENTION

The following detailed description and appended drawings describe andillustrate various embodiments of the invention. The description anddrawings serve to enable one skilled in the art to make and use theinventions, and are not intended to limit the scope of the invention inany manner.

Referring to FIGS. 1, 4, 5, and 7-9 wherein like numerals indicatecorresponding parts throughout the several views, is an exemplaryembodiment of a heat exchanger assembly 20 having split mini-louveredfins 150 of the current invention. The split mini-louvered fins 150enable greater heat transfer efficiency by allowing greater louverpenetration into the air flow channels 36 to increase the distance thatthe air flow has to travel through the heat exchanger core 34 and toincrease the number of boundary layer interruptions that the air flowhas to encounter, while minimizing the pressure drop.

Shown in FIG. 1 is a perspective front view of an exemplary embodimentof the heat exchanger assembly 20 of the present invention, whichincludes a first manifold 22 extending along a manifold A-axis and asecond manifold 24 extending in a spaced and substantially parallelrelationship with the first manifold 22. The first and second manifolds22, 24 present a plurality of corresponding tube slots 26 axially spacedalong the respective manifolds 22, 24. A plurality of fluid tubes 28 isinserted into the corresponding tube slots 26 of the manifolds 22 in aspaced and parallel arrangement for hydraulic fluid communicationbetween the manifolds 22, 24. A plurality of corrugated fins 32 isdisposed between and in thermal contact with adjacent fluid tubes 28 forincreased heat transfer efficiency between the fluid in the tubes 28 andambient air. The plurality of tubes 28 and corrugated fins 32 betweenadjacent tubes 28 define the heat exchanger core 34. The spaces betweenthe corrugated fins 32 and the plurality of tubes 28 define a pluralityof airflow channels 36 through the core 34.

In a normal operating state, a stream of ambient air is directed throughthe core 34 of the heat exchanger assembly 20 to transfer heat from afluid flowing through the fluid tubes 28 to the ambient air. Heat isconducted through the walls of the tubes 28, into the fins, andtransferred to the stream of air flow. It should be appreciated thatheat may be transferred to the fluid flowing through the tubes 28 if thetemperature of the stream of air is higher than the temperature of thefluid flowing through the tubes 28.

Shown in FIG. 2 is a view of a prior art corrugated louvered fin 50having single louvers 52 along a planar portion 54 of the fin 50. Thecorrugated louvered fin 50 is formed from a thin strip of heatconductive material into corner portions 56 and planar portions 54 thatare alternately continuously arranged to define a corrugation. Each ofthe planar portions 54 includes a leading edge 58 oriented into theoncoming air flow, an opposite trailing edge 60 spaced from the leadingedge 58, and a plurality of louvers 52 therebetween. Each louver 52 isdefined by a louver segment 62 of the planar portion 54 between a pairof slits 64. Best shown in FIGS. 2 and 6, on opposite ends of the louversegment 62 is a juncture 66 that transitions the louver segment 62 tothe planar portion 54. The single louvers 52 are formed by pivoting thelouver segments 62 about the junctures 66 such that the louver segments62 are oblique to the planar portion 54. Best shown in FIG. 3, thepivoting of the louver segment 62 about the juncture 66 defines atwisted transition that connects the single louver 52 to the planarportion 54. The louver 52 includes a front edge 59 oriented toward thedirection of air flow and an opposite rear edge 60. The front edges 59of the louvers 52 are substantially parallel with each other and may beparallel with the leading edge 58 of the planar portion 54.

Shown in FIGS. 4, 5, and 7 are views of an embodiment of a corrugatedsplit mini-louvered fin 150 of the current invention. Best shown in FIG.7, each pair of split mini-louvers 152 is defined by pivoting a louversegment 162 about a primary juncture 166 to a predetermined first anglerelative to the planar portion 154, splitting the louver segment 162into a first mini-louver 176 and a second mini-louver 178, counteroff-setting the mini-louvers 176, 178 onto both sides of the planarportion 154, and pivoting the mini-louvers 176,178 about theirrespective secondary junctures 172 to a predetermine second angle withrespect to the planar portion 154. Show in FIGS. 8 and 9, themini-louvers 176, 178 may also be off-set in the axial direction withrespect to the direction of airflow such that a portion of onemini-louver overlaps with a portion of the other mini-louver.

Shown in FIGS. 4 and 7, the split mini-louvered fin 150 includes aplanar portion 154 having a leading edge 158 and an opposite trailingedge 160. The planar portion 154 includes a louver segment 162 definedbetween a pair of primary slits 164 having a first length L1. Onopposite ends of the louver segment 162 is a primary juncture 166 thattransitions the louver segment 162 to the planar portion 154. The louversegment 162 is split into a first segment 168 and a second segment 170by an intermediate slit 165 having a length L2 between the pair ofprimary slits 164. The length L2 of the intermediate slit is shorterthan the length of the primary slit L1, thereby defining a secondaryjuncture 172 on opposite sides of each of the first and second segments168, 170. The secondary junctures 172 transition the respective segments168, 170 into the primary juncture 166, which then transitions into theplanar portion 154. The pair of primary slits 164 and intermediate slit165 may be parallel with each other and as well as with the leading edge158 of the planar portion 154.

Shown in FIG. 7 is a cross-sectional view of the split mini-louveredfins 150 of FIG. 5 along line 7-7. The louver segment 162 is pivoted ina first direction about the primary juncture 166 to a first angle thatis oblique to the planar portion 154. A first mini-louver 176 and asecond mini-louver 178 are then defined by counter-offsetting the firstand second segments 168, 170 onto opposite sides of the planar portion154. While only two mini-louvers 176, 178 are shown per louver segment162, it should be appreciated that additional mini-louvers 176 may beformed on the same louver segment 162 by providing additionalintermediate splits 165 between the pair of primary slits 164.

The counter-offsetting of the first and second segments 168, 170 todefine the first and second mini-louvers 176, 178 may be accomplished bymechanically displacing the material defining the secondary junctures172 such that one of the first and second mini-louvers 176, 178 is onone side of the planar portion 154 and the other of the first and secondmini-louvers 176, 178 is on the other side of the planar portion 154.Once off-set, the first and second mini-louvers 176, 178 may beindividually pivoted about their respective secondary junctures 172 to apredetermined angle with respect to the planar portion 154. Thepredetermined degree of angle for the first and second mini-louvers 176,178 may be the same or offset from each other.

As an alternative to mechanically displacing the material defining thesecondary junctures 172 such that one of the first and secondmini-louvers 176, 178 are on opposite side of the planar portion 154,the counter-offsetting of the first and second segments 168, 170 todefine the first and second mini-louvers 176, 178 may be accomplished bypivoting the first and second segments 168, 170 in a second directionopposite that of the first pivot direction of the louver segment 162such that one of the first and second mini-louvers 176, 178 is on oneside of the planar portion 154 and the other of the first and secondmini-louvers 176, 178 is on the other side of the planar portion 154.The pivoting of the first and second segments 168, 170 in a seconddirection opposite that of the first pivot direction may be variedaccording to the desired angle of the mini-louvers 176, 178 with respectto the planar portion 154.

FIG. 8 shows a cross-sectional view of an alternative embodiment of thesplit mini-louvered fins 150 of FIG. 5 along line 7-7. The firstmini-louver 176 includes a front edge 159 a oriented in the direction ofair flow and a downstream rear edge 161 a. Similarly, the associatedsecond mini-louver 178 includes a front edge 159 b oriented in thedirection of air flow and a downstream trailing edge 161 b. The offsetfirst and second mini-louvers 176, 178 are displaced axially relative tothe direction of air flow from the leading edge 158 to the trailing edge160 such that a portion of the first and second mini-louvers 176, 178overlaps each other in way that the rear edge 161 a of the firstmini-louver 176 extends rearward pass the front edge 159 b of the secondmini-louver 178.

FIG. 9 shows a cross-sectional view of the alternative embodiment of thesplit mini-louvered fins 150 of FIG. 5 along line 9-9. The counteroff-setting of the first and second mini-louvers 176, 178 onto bothsides of the planar portion 154 allows the mini-louvers 176, 178 toextend at a greater distance from the planar portion 154 into the flowchannel 36 than what a single larger louver 52 would allow. The greaterlouver penetration into the air flow channels 36 increases the distancethat the air flow has to travel and increases the number of boundarylayer interruptions that the air flow has to encounter, therebyincreasing heat transfer efficiency. Furthermore, the intermediate slit165 separating the first from the second mini-louver 176, 178 in eachpair of mini-louvers 176, 178 defines an air flow passageway 190 therebyallowing greater air flow efficiency, resulting in less air pressuredrop associated with the change in airflow direction caused by the finsand louvers.

While the invention has been described with reference to an exemplaryembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

Having described the invention, it is claimed:
 1. A heat exchangerassembly comprising: at least one header; a plurality of fluid tubes inhydraulic communication with said header, wherein said tubes are spacedapart; and a plurality of corrugated fins disposed between and inthermal contact with said tubes, at least one of said corrugated finscomprises: a planar portion having a louver segment defined between apair of primary slits, wherein said louver segment includes at least oneintermediate slit between said pair of primary slits thereby splittingsaid louver segment into at least two mini-louvers.
 2. The heatexchanger assembly of claim 1, wherein: said primary slits and said atleast one intermediate slit are parallel, each of said primary slitincludes a length L1, said at least one intermediate slit includes alength L2, and wherein said length L2 is less than said length L1,thereby defining a primary juncture transitioning said louver segment tosaid planar portion and defining a secondary juncture transitioning saidmini-louvers to said primary juncture.
 3. The heat exchanger assembly ofclaim 1, wherein said louver segment includes a primary juncturetransitioning said louver segment to said planar portion, and saidlouver segment is pivoted about such primary juncture such that saidlouver segment is oblique relative to said planar portion.
 4. The heatexchanger assembly of claim 3, wherein each of said mini-louversincludes a secondary juncture transitioning said mini-louvers to saidprimary juncture.
 5. The heat exchanger assembly of claim 4, whereinsaid mini-louvers are counter-offset such that one of said mini-louversis on one side of said planar portion and other one of said mini-loveris on the other side of said planar portion.
 6. The heat exchangerassembly of claim 5, wherein each of said mini-louvers is pivoted aboutrespective said secondary junctures such that each of said mini-louversegment is oblique relative to said planar portion.
 7. The heatexchanger assembly of claim 6, wherein each of said mini-louversincludes a front edge and an opposite trailing edge, wherein saidmini-louvers partially overlap one another such that the rear edge ofone mini-louver extends past the front edge of the other saidmini-louver.
 8. The heat exchanger assembly of claim 7, wherein saidplanar portion includes a leading edge, and wherein said front edges ofsaid mini-louvers are parallel with said leading edge of said planarportion.
 9. The heat exchanger assembly of claim 5, wherein saidintermediate slit defines an air passageway between said mini-louvers oneither side of said planar portion.
 10. A split mini-louver for a heatexchanger assembly, comprising: a planar portion having a louver segmentdefined between a pair of primary slits, wherein said louver segmentincludes at least one intermediate slit between said pair of primaryslits, thereby splitting said louver segment into at least twomini-louvers.
 11. The split mini-louver for a heat exchanger assembly ofclaim 10 wherein said mini-louvers are counter-offset such that one ofsaid mini-louvers is on one side of said planar portion and other one ofsaid mini-lover is on the other side of said planar portion.
 12. Thesplit mini-louver for a heat exchanger assembly of claim 11 wherein saidintermediate slit defines an air passageway between said mini-louvers.13. The split mini-louver for a heat exchanger assembly of claim 12wherein each of said mini-louvers includes a front edge and an oppositetrailing edge, wherein said mini-louvers partially overlap one anothersuch that the rear edge of one mini-louver extends past the front edgeof the other said mini-louver.
 14. The split mini-louver for a heatexchanger assembly of claim 13 wherein each of said mini-louverstransitions into a secondary juncture.
 15. The split mini-louver for aheat exchanger assembly of claim 13 wherein each of said secondaryjuncture transitions into primary juncture which transitions into saidplanar portion.